Subtract 20/21 from 9/30
9/30 - 20/21 is -137/210.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 30 and 21 is 210
Next, find the equivalent fraction of both fractional numbers with denominator 210 - For the 1st fraction, since 30 × 7 = 210,
9/30 = 9 × 7/30 × 7 = 63/210 - Likewise, for the 2nd fraction, since 21 × 10 = 210,
20/21 = 20 × 10/21 × 10 = 200/210 - Subtract the two like fractions:
63/210 - 200/210 = 63 - 200/210 = -137/210
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 18/30-20/21 9/30-40/21 9/60-20/21 9/30-20/42 27/30-20/21 9/30-60/21 9/90-20/21 9/30-20/63 45/30-20/21 63/30-20/21